Five-year results of two cemented hip stem models each made of two different alloys

Abstract

The aim of this study was to compare the influence of two different cemented hip stems each made of two different alloys concerning survival and outcome. The 5-year results with 161 Mueller straight stems made of cobalt chromium (SS CoCr), 272 Mueller straight stems made of titanium (SS Ti), 233 Mueller SL stems made of titanium (SL Ti) and 255 SL stems made of cobalt chromium (SL CoCr) implanted consecutively in this order were compared. All patients were followed up prospectively during the first 5 years after implantation. The evaluation of the results was retrospective. The survival rates for aseptic loosening were 100% (SS CoCr), 92.8% (SS Ti), 81.6% (SL Ti) and 97.8% (SL CoCr). Clinical and radiological outcomes like pain occurrence, use of pain medication, ability to climb stairs, amount of stem subsidence and osteolysis correlated statistically significantly with the results of the survival rates. Concerning the two alloys, chromium cobalt showed better results, and concerning the two designs, the straight stem had a better outcome. For the four prostheses being compared, the results were influenced more by the alloy than by the design, and the small-sized titanium stems were more susceptible to undergoing revision than the large-sized prostheses. Stem design and even more alloy may influence the survival rate and clinical outcome. Evaluating the results, we recommend the use of the classic straight stem prosthesis made of cobalt chromium.